A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: Thu 8 Feb 2018
Source: FarmingUK [edited]
<https://www.farminguk.com/news/-Devastating-crop-pathogen-could-re-emerge-due-to-perfect-storm-of-conditions-_48573.html>
Farmers and scientists must prepare for the potential re-emergence of a crop pathogen, following the discovery of a single wheat plant infected with stem rust - the first confirmed case in the UK in over
60 years. Dr Diane Saunders and Dr Brande Wulff, John Innes Centre, led a global team [that] showed that the UK strain belongs to the Digalu race, which was responsible for a devastating outbreak of stem rust in Ethiopia in 2013, and smaller outbreaks in Sweden, Denmark and Germany [see ProMED-mail posts http://promedmail.org/post/20140327.2360315,
http://promedmail.org/post/20140404.2379670].
Over 80 per cent of UK wheat varieties are susceptible to the UK strain. Changes in climate suggest increasingly conducive conditions for fungi. In addition to the lack of resistance in European wheat varieties, barberry (_Berberis vulgaris_), habitat for the endangered Barberry Carpet moth, has been [planted] increasingly. [It] plays a key role in the life cycle of several rust pathogens including wheat stem rust.
There is the potential for stem rust to become an ever-increasing threat across Europe. Re-initiation of resistance breeding and precluding planting of barberry near arable land, [to] limit the ability of the pathogen to rapidly overcome any introduced resistance and/or climatic constraints, [would] safeguard European cereals from a large-scale re-emergence of wheat stem rust.
--
Communicated by: ProMED-mail <promed@promedmail.org>
[Wheat stem rust is caused by the fungus _Puccinia graminis_ f. sp. _tritici_. Overall yield losses of up to 80 per cent are reported, but some fields are totally destroyed. Stem rust spores are spread by wind and with infected straw or other contaminated materials. Some grasses or volunteer wheat may generate a "green bridge" providing inoculum for the next cropping season. Disease management may include fungicide applications, control of volunteer wheat and resistant varieties if available.
Races with increased virulence are emerging frequently and resistance breeding programmes have been set up by several countries or international groups. One of the most serious threats at present is considered to be the Ug99 family of strains (first discovered in Uganda in 1999), which have overcome the major resistance gene Sr31 used in our current wheat varieties, as well as additional resistance genes in subsequent variants.
However, new strains not related to Ug99 are also posing a danger, for example, the Digalu strain above, named after the wheat variety on which it was first detected (ProMED-mail posts http://promedmail.org/post/20170206.4820305,
http://promedmail.org/post/20140327.2360315). It is now present in the Middle East, East Africa and, after outbreaks in Sicily in 2016, threatening the Mediterranean region. Variants with virulence to 4 additional host resistance genes have been identified in Germany and Denmark and there appear to be 2 distinct genotypes (A and B) of Digalu. A similar situation and association with barberry as described for the UK above has been reported recently also from Sweden (see link below).
Digalu is rapid and destructive. It has overcome two genes effective against Ug99 and recombinants of the two races would pose a high risk of becoming even more aggressive than the parents. Of the more than 50 known wheat resistance genes to stem rust, only very few are currently left that have not been overcome by a stem rust race.
Maps
UK (with counties):
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif>
UK regions:
<http://www.picturesofengland.com/mapofengland/regions.html>
Europe, overview:
<http://www.edinphoto.org.uk/0_MAPS/0_map_europe_political_2001_enlarged.jpg>
Pictures
Stem rust symptoms on wheat:
<http://www.ars.usda.gov/images/docs/9910_10104/stemrust_inset.jpg>
and
<https://www.irinnews.org/photo/201010281134020344/close-shot-ug99-infested-wheat-crop>
(Ug99)
Stem rust (Ug99) effect on resistant vs. susceptible wheat cultivars:
<https://www.irinnews.org/photo/201010281129340750/201010281129340750jpg>
Links
Additional news stories:
<https://phys.org/news/2018-02-decades-forgotten-crop-pathogen-critical.html>
<https://www.reuters.com/article/us-wheat-pest-europe/scientists-fear-resurgence-of-devastating-wheat-disease-in-britain-europe-idUSKBN1FS1C5>
<https://www.thetimes.co.uk/article/plague-that-scared-the-romans-is-back-g6nzm5d0k>
and
<http://www.edp24.co.uk/business/farming/norwich-sientists-action-call-on-stem-rust-threat-1-5388298>
Source research report (open access):
<https://www.nature.com/articles/s42003-018-0013-y>
Information on wheat stem rust:
<http://www.ars.usda.gov/Main/docs.htm?docid=9910>,
<http://www.agbioworld.org/newsletter_wm/index.php?caseid=archive&newsid=2686>,
<http://science.sciencemag.org/content/358/6370/1541.full> (resistance
breeding) and via
<http://www.ars.usda.gov/Main/docs.htm?docid=14649>
Information on strain Digalu:
<http://rusttracker.cimmyt.org/?page_id=6811> and <https://apsjournals.apsnet.org/doi/full/10.1094/PHYTO-11-14-0302-FI>
Digalu in Sweden:
<https://www.slu.se/en/ew-news/2017/11/stem-rust-attacks-in-sweden-heralds-the-return-of-a-previously-vanquished-foe/>
New stem rust race in the Americas:
<https://apsjournals.apsnet.org/doi/full/10.1094/PDIS-08-17-1161-PDN>
Stem rust strains nomenclature:
<http://www.fao.org/agriculture/crops/rust/stem/stem-pathotypetracker/stem-racenomenclature/en/>
_P. graminis_ taxonomy and synonyms:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=159822>
and
<http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=159822>
Updates of worldwide distribution of stem rust strains via:
<http://rusttracker.cimmyt.org/>
Global Rust Initiative:
<http://www.globalrust.org/>
- Mod.DHA]
[See Also:
2017
----
Stem & stripe rusts, wheat - Europe, Asia, Africa: new races
http://promedmail.org/post/20170206.4820305
Stripe, stem & leaf rusts, wheat - Ethiopia
http://promedmail.org/post/20161117.4637042
Stem rust Ug99 group, wheat - Egypt: 1st report
http://promedmail.org/post/20160322.4109568
2015
---
Stem rust, wheat - Kenya: new strain, correction
http://promedmail.org/post/20150205.3144036
Stem rust, wheat - Kenya: new strain
http://promedmail.org/post/20150204.3141068
2014
----
Stem rust, wheat - Germany: strains
http://promedmail.org/post/20140404.2379670
Stem rust, wheat - Ethiopia (02): strains
http://promedmail.org/post/20140327.2360315
Stem rust, wheat - Ethiopia: (southern) alert
http://promedmail.org/post/20140109.2162758
2012
---
Stem & stripe rusts, wheat: double resistance breeding
http://promedmail.org/post/20120831.1274190
Stem rust, wheat - Africa: new races
http://promedmail.org/post/20120607.1159076
2011
---
Wheat stem rust, Ug99 group - Zimbabwe, Mozambique: new races
http://promedmail.org/post/20110824.2574
2010
---
Wheat stem rust, Ug99 - Kenya: (RV), update
http://promedmail.org/post/20101103.3976
Wheat stem rust, Ug99 group: new races
http://promedmail.org/post/20100602.1834
and older items in the archives]
Topics
Species
